Ammonia gas sensors with vanadium-based sensing electrode

1. An ammonia gas sensor, comprising:

an electrolyte;

a reference electrode in contact with the electrolyte; and

an ammonia selective sensing electrode in contact with the electrolyte spaced apart from the reference electrode, said ammonia selective sensing electrode comprising a vanadium-based material selected from the group consisting of vanadium silicide, vanadium oxysilicide, vanadium carbide, vanadium oxycarbide, vanadium nitride, and vanadium oxynitride.

2. The ammonia gas sensor in accordance with claim 1 , wherein the electrolyte comprises a material capable of electrochemical transfer of hydrogen ions, oxygen ions, or both hydrogen and oxygen ions.

3. The ammonia gas sensor in accordance with claim 2 , wherein the electrolyte is a zirconia composition.

4. The ammonia gas sensor in accordance with claim 3 , wherein the zirconia composition comprises zirconia containing an additive adapted to stabilize the zirconia at elevated temperatures.

5. The ammonia gas sensor in accordance with claim 4 , wherein the electrolyte is yttria-stabilized zirconia.

6. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material is doped with an electrically conducting metal selected from the group consisting of bismuth, lead, lithium, lanthanum, strontium, cerium, calcium, manganese, iron, copper, gadolinium, nickel, neodymium, zinc, tin, indium, yttrium, samarium, gold, titanium, and magnesium.

7. The ammonia gas sensor in accordance with claim 6 , wherein the electrically conducting metal is present in the vanadium-based material in an amount between about 0.1 at. % to about 15 at. %.

8. The ammonia gas sensor in accordance with claim 6 , wherein the electrically conducting metal is present in the vanadium-based material in an amount between about 1 at % to about 10 at %.

9. The ammonia gas sensor in accordance with claim 6 , wherein the electrically conducting metal is present in the vanadium-based material in an amount between about 3 at % to about 8 at %.

10. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material further comprises a chemically stabilizing dopant.

11. The ammonia gas sensor in accordance with claim 10 , wherein the chemically stabilizing dopant is selected from the group consisting of tantalum, niobium, and magnesium.

12. The ammonia gas sensor of claim 10 , wherein the chemically stabilizing dopant is present in the vanadium-based material in an amount between about 0.1 at % to about 5 at %.

13. The ammonia gas sensor in accordance with claim 10 , wherein the chemically stabilizing dopant is present in the vanadium-based material in an amount between about 0.3 at % to about 3 at %.

14. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material further comprises a diffusion-impeding dopant.

15. The ammonia gas sensor in accordance with claim 14 , wherein the diffusion-impeding dopant is selected from the group consisting of zinc, zirconium, lead, iron, and yttrium.

16. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material comprises vanadium silicide or vanadium oxysilicide.

17. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material comprises vanadium carbide or vanadium oxycarbide.

18. The ammonia gas sensor in accordance with claim 1 , wherein the vanadium-based material comprises vanadium nitride or vanadium oxynitride.

19. A process for measuring the concentration of ammonia in a gas, the process comprising

providing an ammonia gas sensor comprising an electrolyte, a reference electrode in contact with the electrolyte; and an ammonia selective sensing electrode in contact with the electrolyte spaced apart from the reference electrode, said ammonia selective sensing electrode comprises vanadium-based material selected from the group consisting of vanadium silicide, vanadium oxysilicide, vanadium carbide, vanadium oxycarbide, vanadium nitride and vanadium oxynitride;

contacting the gas with the ammonia selecting sensing electrode; and

measuring a voltage signal between said ammonia sensing electrode and said reference electrode.

20. The process in accordance with claim 19 , wherein the vanadium-based material is doped with an electrically conducting metal selected from the group consisting of bismuth, lead, lanthanum, lithium, zinc, tin, indium, strontium, cerium, calcium, copper, manganese, gadolinium, nickel, neodymium, yttrium, samarium, gold, titanium, and magnesium.

21. The process in accordance with claim 20 , wherein the electrically conducting metal is present in the vanadium-based material in an amount between about 0.1 at. % to about 15 at. %.